The present invention relates to lighting equipment for a vehicle in which a portion to be welded in a lighting equipment body for forming lighting equipment for a vehicle, such as a marker lamp for an automobile, and a portion to be welded in such as a front lens for covering its opening are directly welded together by vibration which is caused in a welding portion between the two members. More particularly, the present invention relates to a method and apparatus for vibration welding of lighting equipment for a vehicle for effectively performing vibration welding by preventing resonance of the lighting equipment body on the fixed side during the vibration welding of the two members.
Hitherto, there has been proposed lighting equipment which is manufactured by a so-called vibration welding process in which a lighting equipment body 51 or the like formed of a thermoplastic synthetic resin and a front lens 52 or the like formed similarly of a thermoplastic synthetic resin are welded together by subjecting their portions to be welded to vibration welding. In the lighting equipment for a vehicle which is manufactured by this process, welding is effected as follows: Welding legs 54 of such as the front lens 52 are brought into contact with joining surfaces 53 of flange portions or the like of the lighting equipment body 51 of the equipment for a vehicle, the two members in a state of contact with each other are held under pressure, one member is caused to undergo vibration with respect to the other member to generate frictional heat, thereby allowing the welding legs 54 of such as the front lens 52 to be fitted to the fused joining surfaces 53 of such as the lighting equipment body 51 to be fitted. As shown in FIG. 9, the lighting equipment for a vehicle which is manufactured by this kind of vibration welding is manufactured by a vibration welding apparatus which operates as follows: The lighting equipment body 51 side with its joining surfaces 53 facing up is fitted in a body receiving jig 55, and the front lens 52 is fitted in a lens receiving jig 56 in a state in which distal ends of the welding legs 54 oppose the joining surfaces 53 of the aforementioned lighting equipment body 51. Subsequently, after, generally, both the body receiving jig 55 and the lighting equipment body 51 are raised, and the joining surfaces 53 are pressurized (in the direction of arrow Y) to abut against the welding legs 54 on the front lens 52 side fitted in the lens receiving jig 56, and the lens receiving jig 56 side, i.e., the front lens 52, is caused to undergo vibration (in the direction of arrow X) so as to generate frictional heat between the distal ends of the welding legs 54 and the joining surfaces 53, thereby partially fusing and joining the joining surfaces 53 and the welding legs 54.
However, with the above-described conventional vibration welding apparatus, if the front lens 52 side is vibrated, due to such as changes in various conditions, including the strength of pressure contact on the lighting equipment body 51 side and the relative size of the contact surfaces of the two members, the lighting equipment body 51, particularly the joining surfaces 53 which are portions of abutment with respect to the welding legs 54 of the front lens 52, resonate with the vibration of the front lens 52. Consequently, there is a problem in that frictional heat of a measure necessary for vibration welding is not generated, making welding impossible. As a measure against such a problem, there has been proposed a method in which turnup portions (not shown) which engage in grooves or the like formed in the body receiving jig 55 are fitted outside the joining surfaces 53 of the lighting equipment body 51 so as to prevent resonance. However, depending on the shape of the lighting equipment for a vehicle, particularly the lighting equipment body 51, there are cases where the turnup portion cannot be formed. In addition, in the case of the lighting equipment body 51 which is formed into a flat shape with a shallow bottom, since the portion fitted into the body receiving jig 55 is short, there has been a problem in that the lighting equipment body 51 moves in conjunction with the vibration of the front lens 52, and is disengaged from the body receiving jig 55, so that the welding operation cannot be performed.